Pressure-filling of containers

ABSTRACT

A method of pressure-filling a container includes placing its opening tightly against a filling element, extending a return gas tube into the container, causing and measuring a progression of pressures in the container&#39;s interior, thereby generating a measured progression of pressures, generating a signal indicative of the measured progression of pressures, recording it, monitoring it for information indicative of a pressure peak, identifying such information, comparing a measured value of the pressure peak with a reference value, measuring an absolute pressure at a point in time at which the pressure peak is measured, based at least in part this measurement, determining that the pressure peak is caused by the filling-material level having reached the return gas tube, and upon making the determination, transmitting closing the filling element.

RELATED APPLICATIONS

This is the national stage under 35 USC 371 of international applicationPCT/EP2015/075102, filed on Oct. 29, 2015, which claims the benefit ofthe Nov. 7, 2014 priority date of DE102014116267.6, the contents ofwhich are incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to filling containers with liquid fillingmaterial, and in particular, to pressure filling.

BACKGROUND

In a known filling process, a return gas tube of a filling elementextends into a container and conveys away gas displaced from thecontainer as liquid filling material enters the container. A pressuresensor connected to either the container's interior or a return gas linemeasures the pressure over the entire filling process and sends acorresponding signal to an evaluating device. The evaluating devicerecords the progression of pressure over time for the entire fillingprocess and compares the result with desired values. From thiscomparison, a controller of the filling device detects whether thefilling process is proceeding correctly. The controller may also bringabout a change in the process cycle as a result of the pressureprogression determined by the evaluating device.

SUMMARY

An object of the invention is to provide a method for thepressure-filling of containers in a way that makes it simpler to controlthe filling process.

According to the invention, the filling element of the filling device iscontrolled as a function of an output signal from the evaluating device.The evaluating device monitors the pressure progression, and inparticular, the occurrence of a pressure peak that occurs when thefilling-material level in the container reaches the return gas tube.When this pressure peak is detected, a closing signal is sent to thefilling element. In response, the filling element immediately stopsdelivering filling material into the container. The closing signal canbe a switching signal of the evaluating device that is eithertransmitted to the controller of the filling device that controls thefilling element, or is sent directly to the filling element. If theevaluating device is part of the controller of the filling device, thenthe closing signal is generated in the controller itself. According tothe invention, the closing of the filling element, which is usuallyrealized by a filling valve, is made directly dependent on the signal ofthe pressure sensor. As a result, the filling element or filling valvecloses immediately upon detection of the pressure peak in question. Aseal seat in the filling valve is usually closed for this purpose.

In the method described herein, the pressure progression is not used tomodify the entire filling process. Instead, the detection of a certainpressure peak in the pressure progression is directly used to derive theclosing signal for the filling valve.

The invention is thus based in part on the recognition that a smallpressure peak always occurs in the pressure progression when thefilling-material level in the container reaches the return gas tube. Inaddition, the invention is based in part on the realization that thispressure peak can be used as a trigger for closing the filling element.The invention therefore facilitates a very simple control of the fillingprocess, above all, towards the end of the filling process. Theinvention obviates the need for an additional fill-level sensor. Thisrepresents a significant advantage. Elimination of the fill-level sensorsimplifies or eliminates considerable electrical cabling. Additionally,the considerable cost of the fill-level sensor is saved.

The terms “filling element” and “filling valve” are used synonymouslyhereinafter.

As already described above, the evaluating device can be a separate unitor part of a controller of the filling device. It is also possible torealize the evaluating device and its components as software implementedin a controller of the filling device. Individual components of theinvention can be provided singly or in multiples. In addition it is alsopossible to use the pressure progression to control the entire fillingprocess.

In order for the evaluating device to record the pressure peak from thepressure progression, the first chronological derivation of successivepressure values is used for the detection of the pressure peak. Thisfirst chronological derivation is then compared with a reference value.When the reference value is reached, it is assumed that the pressurepeak, which indicates that the filling-material level has reached thereturn gas tube, is present, whereupon the closing signal for thefilling element or a switching signal is immediately output, eitherdirectly to the filling element or to the controller of the fillingdevice, for closing the filling element.

According to the invention, the absolute pressure at the time when thepressure peak is detected is also taken into account. In this way, it ispossible to prevent any other pressure peak in the filling process frombeing used other than the one at which the rising filling-material levelreaches and/or closes off the lower end of the return gas tube. Bytaking into account the absolute pressure, it can therefore be ensuredthat the pressure peak is present at a pressure level that should bepresent when the desired pressure peak is present, which occurs at theend of the filling process when the return gas tube is closed off by therising filling-material level.

Preferably, the pressure measurements over a period of 0.1-3 seconds areused for the detection of the pressure peak. The successive pressuremeasurements over a period of time such as this are well suited todetermining pressure plateaus and pressure peaks in a pressureprogression.

Preferably, the difference between the last 5 to 50 pressuremeasurements and an average of pressure measurements over the last 1 to3 seconds can be determined for the detection of the pressure peak. Thispressure differential is compared, for example, with a reference value,with the pressure peak in question assumed to be present when thatreference value is reached or exceeded.

The pressure peak that occurs when the rising filling-material levelreaches the end of the return gas tube has not previously been used forprocess control in the filling process. The present invention does this.In doing so, it simplifies process control, especially at the end of thefilling process.

In addition the pressure differential between the foot and vertex of thepressure peak can also be taken into account for the detection of thepressure peak. This ensures consideration of only those pressure peakshaving a certain minimum amplitude.

When filling containers that have an upwardly narrowing innercross-sectional area, a first pressure peak in the pressure progressiondoes not usually occur until the filling-material level rising in thecontainer reaches the region in which the cross-sectional area begins totaper. A braked filling, i.e., a slower filling of the container, beginswhen this tapering level is reached. Provision can now be made for onlythe pressure peaks that occur after the start of the braked filling tobe taken into consideration. In this way, all pressure peaks previouslyoccurring in the filling process are disregarded. This increases thecertainty of detecting the correct pressure peak, namely the one thatcorresponds to the filling-material level in the container havingreached the return gas tube.

When containers are pressure-filled, the container is preferablypre-purged with an inert gas, if applicable after multiple cleaningrinses with air, oxygen or inert gas. The filling process can beaccelerated in this way.

The inventive method allows rapid and reliable control of the fillingprocess. This is especially useful for filling carbonatedfilling-material such as lemonades, beer, cola or the like.

In one aspects, the invention features a device for the pressure-fillingof containers. Such a device has at least one filling element, andpreferably a plurality of filling elements, against each of which acontainer lies tightly by its container opening at least during part ofthe filling process and by which at least one process pressure isapplied to the interior of the container in at least one process stepduring the filling process. The pressure is applied, as a rule, but notnecessarily, with an inert gas. The filling element is connected to atleast one pressure sensor that, during the filling process, senses thepressure in the interior of the container, which is connected to thefilling element, and that provides an electrical signal, whichcorresponds to the pressure, to an evaluating device. During the fillingprocess, a return gas tube of the filling element extends into thecontainer and conveys away the gas displaced from the container as thefilling material fills the container.

In some embodiments, the evaluating device is functionally connected tothe filling element and has a detection device for recording a pressurepeak at the end of a filling process. The pressure peak indicates thatthe filling-material level in the container has reached the return gastube.

The detection apparatus can be implemented in the evaluating device,e.g., by way of software. It can also be provided as a discrete moduleinside or outside the evaluating device. In the same way, the evaluatingdevice can be an independent module. Or it can be integrated into acontroller of the filling device. The detection apparatus has acalculation unit that, from the electrical signal of the pressuresensor, calculates the presence or absence of the pressure peak inquestion. This pressure peak indicates that the filling-material levelhas reached the return gas tube.

Reference is made to the statements in the description of the inventivemethod for the basic considerations and advantages of the inventivedevice.

Preferably, a series of successive pressures measured over a certainperiod of time, e.g. the last 50 to 100,000 measurements, is used forthe calculation of the pressure peak, since this makes it possible todistinguish plateaus from pressure peaks in the pressure progression.The additional consideration of the absolute pressure value makes itpossible to associate plateaus and pressure peaks with certain stages ofthe filling process. The pressure peak that occurs when the return gastube is closed by the rising filling pressure level takes place at theend of the filling process. The evaluating device is thereforepreferably configured so as to be able to associate the presence of adetected pressure peak from the pressure progression with the end of thefilling process such that the association of the pressure peak with thepoint in time in the process when the return gas tube has been reachedby the rising filling-material level is unambiguous.

A time-based controller, which ensures that only pressure peaksoccurring within a certain time window within the pressure progressionof the filling process are captured, can also preferably be used for thedetection of the pressure peak.

The pressure sensor is preferably arranged on a gas channel that isconfigured in the filling element and that is connected to the interiorof the container positioned at the filling element. This gas channel ispreferably the return gas channel located in the filling element andconnected to the return gas tube. The pressure peak that occurs when thereturn gas channel is closed can be detected most clearly in this way.

The term “detect” is used here to mean a recognition process that isbased on the measurements by the pressure sensor as well as oncalculation algorithms of the evaluating device that enable thesemeasurements to be associated with certain events of the fillingprocess.

In some embodiments, the filling device comprises a plurality of fillingelements, with preferably one common evaluating device being providedfor all filling elements.

In other embodiments, the filling element is configured as a fillingvalve. When the filling valve closes, at least one seal seat of thefilling valve closes.

In some embodiments, the filling device is a rotary filling devicecomprising a plurality of container holders and associated fillingelements around its periphery. Rotary filling devices of this type arecurrently in general use and reliable in operation as well as beingcomparatively space-saving.

In other devices, the filling device is an in-line filling device, suchas a linear container-filling machine, in which the filling elements arearranged in a line relative to one another and in which the containersmove in a straight line through the container-filling machine. Otherembodiments include those in which a filling device has only one fillingelement.

Both the detection apparatus of the evaluating device and the evaluatingdevice itself can be software-implemented in a controller of the fillingdevice. In many embodiments, the filling device's controller is based ona processor.

The embodiments of the invention described above can be combined withone another in any desired manner provided this is not technicallyinconsistent.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below by way of example by reference to theschematic drawing in which:

FIG. 1 shows a partial-section view of part of a filling device with afilling valve and a container;

FIG. 2 shows a plot of a conventional pressure progression as recordedin the evaluating device in FIG. 1, and

FIG. 3 shows a schematic diagram of a pressure progression during thefilling of a container that has an upwardly narrowing containercross-section.

DETAILED DESCRIPTION

FIG. 1 shows a filling element in the form of a filling valve 10 of arotary filling device 8 in detail, preferably as a filling valve withouta filling tube. A housing 12 that houses the filling valve 10 defines aliquid channel 14 in which is arranged a seal seat 16. An actuator opensthe seal seat 16 at the start of the filling process and closes it atthe end of the filling process.

FIG. 1 shows the seal seat 16 in its open position. The filling valve 10is arranged on an outer part of a rotor 11 of the rotary filling device8. However the filling valve 10 may also be arranged on an in-linefilling device or the like.

The liquid channel 14 connects to an annular tank 18 arranged coaxiallyon the rotor 11. The annular tank 18 defines a filling material chamber20 and a gas space 22 above the filling material chamber 20. An inertgas, such as carbon dioxide gas, fills the gas space 22.

A filling material line 24 supplies the filling material chamber 20 withthe liquid filling material in such a way that the level N of fillingmaterial in the annular tank 18 is regulated to a specified orpre-selected value. A pre-tensioning gas line 26 supplies the gas space22 with the pressurized inert gas at constant or essentially constantpressure.

A number of devices are provided on the rotor 11 and shared by all thefilling valves 10. These devices include a pre-tensioning gas ringchannel, a supply line 30 that connects the pre-tensioning gas ringchannel 28 to the gas space 22, a first return gas ring channel 32 forpreliminary pressure relief, and in which a pressure equal to the reliefpressure is maintained, a second return gas ring channel 34 connected tothe atmosphere for further pressure relief, and a vacuum ring channel 36connected to a vacuum source.

Each filling valve 10 has a return gas tube 38. When a bottle 40 islocated at the filling valve 10, the a lower open end of the return gastube 38 opens out into the interior of the bottle 40.

In addition to defining the liquid channel 14, the housing 12 alsodefines gas paths, among which is a gas channel 42. An upper open end ofthe return gas tube 38 opens out into this gas channel 42.

An individually controllable control valve 44 at each filling valve 10controls the gas paths. Depending on the particular treatment or processstep that a bottle sealed against the filling element 10 is engaged in,the control valve 44 connects that bottle's interior to one of thepre-tensioning gas ring channel 28, the first return gas ring channel 32the second return gas ring channel 34, or the vacuum ring channel 36.This results in a pressure progression, an example of which is shown inFIG. 2 for the case in which the filling valve 10 is working correctly.

The gas channel 42 connects to a pressure sensor 46. Through the returngas tube 38, the pressure sensor 46 constantly records the progressionof pressure present inside the bottle 40 provided at the filling valve10. The pressure sensor 46 delivers the corresponding measurement to anevaluating device 48.

The evaluation device 48 is provided in common for all the fillingvalves 10 or their pressure sensors 46. Preferably, the evaluationdevice 48 includes a computer. In some embodiments, the evaluatingdevice 48 is part of a controller. In others, the evaluating device 48is a discrete function module in addition to the controller.

With the pressure sensors 46 and the evaluating device 48 it is possibleon the one hand to monitor and/or diagnose individual filling valves 10with the machine running, i.e. any malfunction of individual fillingvalves is detected early to allow counter-measures to be taken asrequired. However, an automatic, filling material-specific control ofthe filling process is also possible with the pressure sensors 25 andthe common evaluating device 48.

FIG. 2 shows a graph of a pressure progression 50 which measured by thepressure sensor 46 at the filling valve 10 and recorded by theevaluating device 48 during the filling of a container that has aconstant cross-section, such as a can. The ordinate and abscissarepresent pressure and time respectively.

The pressure progression 50 shows the pressure at the start of thefilling process (step 52), during the container's pre-evacuation (step54) while purging inert gas from the container (step 56), whilepartially pre-charging the container to a pressure P2 (section 58),while pre-charging the container to a charging or filling pressure P1(step 60), and during a rapid filling process (step 62).

The pressure progression 50 also shows the pressure peak 64, at whichpoint the filling-material level in container reaches the return gastube 38. Upon learning about the pressure peak 64, the evaluating device48 closes the seal seat 16.

Following closure of the seal seat 16, the progression 50 continues witha preliminary pressure-relieving step, for example, down to pressure P2(step 66) and a residual pressure relieving step down to atmosphericpressure (step 68). At this point, the pressure progression 50 arrivesat the end of the filling process (step 70).

FIG. 3 shows the pressure progression during the filling of a containerhaving a cross-section that varies. The particular example is for a beerbottle, which has an essentially constant cross section until oneapproaches the bottle's neck. Process steps that are the same as thosein FIG. 2 are provided here with the same reference numbers.

Unlike the pressure progression shown in FIG. 2, the pressureprogression shown in FIG. 3 has first and second pressure peaks 63, 64.

The first pressure peak 63 occurs when the filling-material levelreaches the beginning of the bottle's neck. Within the pressureprogression 50, this occurs in the region of pressure plateau P1. Slowfilling 65, otherwise known as “braked filling,” begins with this firstpressure peak 63. It is important that the evaluating device 48 detectthe second pressure peak 64 and not the first pressure peak 63 as beingthe signal that the filling-material level in the bottle has reached thereturn gas tube. Upon detecting the second pressure peak 64, it closesthe filing valve's seal seat 16. In some embodiments, the start of slowfilling enables detection of the second pressure peak 64.

Having described the invention, and a preferred embodiment thereof, what is claimed as new, and secured by Letters Patent is: 1-7. (canceled)
 8. A method of pressure-filling a container, said method comprising placing said container's opening tightly against a filling element, extending a return gas tube into said container, causing a progression of pressures in said container's interior, measuring said progression of pressures in said container's interior, thereby generating a measured progression of pressures, generating an electrical signal indicative of said measured progression of pressures, recording said electrical signal, thereby generating a recorded electrical signal, monitoring said recorded electrical signal for information indicative of a pressure peak, identifying information indicative of a pressure peak, comparing a measured value of said pressure peak with a reference value, measuring an absolute pressure at a point in time at which said pressure peak is measured, based at least in part on said absolute pressure, determining that said pressure peak is caused by a filling-material level having reached said return gas tube, and upon making said determination, transmitting a closing signal to close said filling element.
 9. The method of claim 8, wherein monitoring said recorded electrical signal for information indicative of a pressure peak comprises monitoring said recorded electrical signal for sufficient time to provide pressure measurements over a period of between one-tenth of a second and three seconds, said pressure measurements to be used for detection of said pressure peak.
 10. The method of claim 8, wherein identifying information indicative of a pressure peak comprises, for each pressure measurement in a set of pressure measurements, determining a difference between said pressure measurement and an average of pressure measurements and comparing said difference with a reference value, wherein said set of pressure measurements comprises a set of between five and fifty preceding pressure measurements and said average of pressure measurements is an average of pressure measurements from a preceding one to three seconds.
 11. The method of claim 8, wherein identifying information indicative of a pressure peak comprises identifying a pressure differential between a foot of said pressure peak and a vertex of said pressure peak, and using said pressure differential as a basis for determining that said pressure peak is caused by said filling-material level having reached said return gas tube.
 12. The method of claim 8, further comprising selecting said container to be a container having a cross-section that decreases with increasing distance from a base of said container, and causing filling of said container to transition from a rapid filling process to a slow filling process, said transition corresponding to a point on said progression of pressures, wherein determining that said pressure peak is caused by said filling-material level having reached said return gas tube comprises doing so based only on pressures in said pressure progression that are after said point.
 13. The method of claim 8, wherein determining that said pressure peak is caused by said filling-material level having reached said return gas tube comprises doing so at least in part on the basis of a time at which said candidate pressure peak occurs in said measured progression of pressures.
 14. The method of claim 8, wherein causing a progression of pressures in said container's interior comprises pre-charging said container with an inert gas prior to entry of liquid-filling material into said container. 